#!/usr/bin/perl

use strict;
use Data::Dumper;

my %h = ();

# stick in some data at varying depths
$h{ 1}{ 2}{ 3} = 123;
$h{1}{3} = 13;
$h{2} = 2;

# this array will collect the values
my @flat = ();

hashTraverse( \%h, \@flat );

print Dumper( \@flat );

sub hashTraverse {
    my ( $href, $aref ) = ( shift(), shift() );
    foreach my $key ( sort keys %$href ) { # this simple example sorts the tree left-right
        my $val = $href -> { $key };
        if ( ref( $val ) eq 'HASH' ) {
            hashTraverse( $href -> { $key }, $aref )
        }
        else {
            push @$aref, $val;
            # or instead whatever else should be done to or with the hash node
        }
    }
}


##</code><code>##

$VAR1 = [
          123,
          13,
          2
        ];